Hurricane Joaquin to Bring ‘Thousand-Year’ Rainfall to the Carolinas

Though it now appears that Hurricane Joaquin won’t make landfall on the United States, it will likely coincide with a storm that will bring a “thousand-year rainfall.”

Even without the hurricane reaching shore, new forecasts say that the effects of the storm will help bring “epic rainfall” to South Carolina, according to the writers at Weather Underground.

“The latest 3-day Quantitative Precipitation Forecast from NOAA’s Weather Prediction Center is calling for 10 – 15″ inches of rain for the majority of South Carolina, including the cities of Charleston and Columbia,” Weather Underground notes.

The latest forecast ascribes the major rainfall to what meteorologists call a “Predecessor Rain Event.” That is when tropical moisture swirling ahead of a landfalling tropical cyclone interacts with a surface front and upper-level trough to produce heavy rainfall. The heavy water-soaked clouds of Hurricane Joaquin is set to interact with the rain storm already forming over the area to bring “epic amounts of rainfall.”

The maximum rainfall predicted to fall in any 24-hour period during the 5-day period from 5 am EDT October 2 to 5 am EDT October 7, according to a high-resolution Weather Research Forecast (WRF) model run done by MetStat, Inc. (http://www.metstat.com.) In some areas of North Carolina and South Carolina, 24-hour rainfall amounts one would expect to fall only once in a thousand years are predicted.

Finally, the site notes that, “According to NOAA’s Precipitation Frequency Data Server, these could be 1-in-1000 year rains for some locations.”

Follow Warner Todd Huston on Twitter @warnerthuston or email the author at igcolonel@hotmail.com